Field of the Invention
The present invention relates to an image forming apparatus that, with respect to a cartridge used in an image forming apparatus such as an electrophotographic printer or a copier, includes a toner supplying mechanism and has a detection unit for detecting a toner remaining amount in a cartridge.
Description of the Related Art
In image forming apparatuses such as electrophotographic copiers or printers, if the image forming apparatus is equipped with a cartridge having a supplying mechanism for toner, detection of the remaining amount of toner is performed after a toner supplying operation as an initial operation in accordance with the remaining amount of toner or the usage situation of members constituting the cartridge. As a method for detecting the remaining amount of toner (hereunder, referred to as “toner remaining amount”), a method is available that detects a light amount that passes through the inside of a cartridge using an optical semiconductor device. Another method for detecting a toner remaining amount that has been proposed is a method that detects the electrostatic capacitance of toner that is formed between a developing roller and an antenna electrode (for example, see Japanese Patent Application Laid-Open No. 2001-228698). According to this method, the electrostatic capacitance of the toner is detected by providing an antenna electrode facing a developing roller that is a developer bearing member and applying an alternating voltage to the developing roller. With respect to this kind of method for detecting the toner remaining amount, in order to reduce detection errors that arise due to a variety of factors when performing calculation of the toner remaining amount, a method has been proposed that calculates an optimal value using a mean value, a maximum value and a minimum value of output values that are sampled during a certain time period (for example, see Japanese Patent Application Laid-Open No. 2004-226933).
However, an error component arises irrespective of which kind of calculation method is adopted. For example, in a case where the toner remaining amount in a process cartridge has decreased, in some cases, even if there is no remaining amount of toner in a toner bottle, an error occurs in a detection operation for detecting the toner remaining amount at the time of an initial operation, and the toner remaining amount that is detected increases to an amount that is more than the actual toner remaining amount.